Liquid inoculants formulated with different polymeric additives viz., polyvinylpyrrolidone PVP, polyethylene glycol (PEG), polyvinyl alcohol PVA and Gum Arabic were evaluated for their ability to support Rhizobium survival on coated seeds. Inoculated faba bean, alfalfa, chickpea, mung bean, guar and soybean seeds were incubated at high temperatures (40°C and 45°C) for 24 and 48 hour. The number of rhizobia per seed of each treatment was determined using the plate count method. Liquid inoculants containing 1% PEG was found to maintain the highest number of cells surviving on faba bean seeds giving 12.4% increase compared to charcoal-based inoculants. Liquid inoculants amended with 0.8% Gum Arabic and 0.1% PEG recorded the maximum population of about 2.4×106 and 2×106 cells/ alfalfa seed, respectively. Highest population 8×105 cells/ chickpea seed was recorded in liquid inoculant formulated with 0.5% Gum Arabic. For mung bean, liquid inoculants amended with 0.1% Gum Arabic was found to record a maximum population of about 1×106 and 9×105 cells/seed after 24 and 48 h of storage at 45°C, respectively. Liquid inoculants amended with 0.1% and 0.5% PVA were found to be better in supporting Rhizobium population on guar seeds than charcoal based inoculants after 48 h. Liquid inoculants containing 0.5 % PVA and 0.1 % Gum Arabic could support the survival of rhizobial cell to 9.6% and 8.1% over charcoal based inoculant after 24 and 48 h from inoculation of soybean seeds at 45°C. The study concluded that liquid formulations could either promote rhizobial population or sustain rhizobial number equivalent to charcoal based inoculants. Moreover, Survivability of liquid formulations varied with the strain, seed and polymeric additives.

Dayamani KJ, Brahmaprakash GP (2014). Influence of form and Concentration of the Osmolytes in Liquid Inoculants Formulations of Plant Growth Promoting Bacteria. International Journal of Scientific and Research Publications.4:(7):1-6